Class 10 Maths Chapter 5 Arithmetic Progressions Exercise 5.2

Question 11 Which term of the A.P. 3, 15, 27, 39, … will be 132 more than its 54th term?

Solution:

Given A.P. is 3, 15, 27, 39, …

a1 = 3

d = a2 – a1 = 15 -3 = 12

a54 = a1 + (54 – 1) d

a54 = 3 + (53) (12)

a54 = 3 + 636

a54 = 639

132 + 639 = 771 We have to find the term of this A.P. which is 771.

Let nth term be 771.

an = a1 + (n − 1) d

771 = 3 + (n – 1) 12

771 – 3 = (n – 1) 12

768 = (n-1) 12

(n-1)=64

n= 65

Therefore, 65th term was 132 more than 54th term. Ans.

Question 12 Two APs have the same common difference. The difference between their 100 th term is 100, what is the difference between their 1000 th terms?

Solution:

Question 17 find the 20th term from the last term of the AP 3,8,13,….. , 253

Solution:

Given A.P. is 3,8,13,….. , 253